1. Field of the Invention
This invention is directed to novel compositions comprising one or more tetramantanes. This invention is also directed to novel processes for the separation and isolation of tetramantane components into recoverable fractions from a feedstock containing one or more tetramantane components.
2. References
The following publications and patents are cited in this application as superscript numbers:
1 Lin, et al., Natural Occurrence of Tetramantane (C22H28), Tetramantane (C26H32) and Hexamantane (C30H36) in a Deep Petroleum Reservoir, Fuel, 74(10):1512-1521 (1995)
2 Alexander, et al., Purification of Hydrocarbonaceous Fractions, U.S. Pat. No. 4,952,748, issued Aug. 28, 1990
3 McKervey, Synthetic Approaches to Large Diamondoid Hydrocarbons, Tetrahedron, 36:971-992 (1980).
4 Wu, et al., High Viscosity Index Lubricant Fluid, U.S. Pat. No. 5,306,851, issued Apr. 26, 1994.
5 Chung et al., Recent Development in High-Energy Density Liquid Fuels, Energy and Fuels, 13; 641-649 (1999).
6 Sandia National Laboratories (2000), World""s First Diamond Micromachines Created at Sandia, Press Release, (Feb. 22, 2000) www.Sandia.gov.
7 Balaban et al., Systematic Classification and Nomenclature of Diamondoid Hydrocarbons-I, Tetrahedron. 34, 3599-3606 (1978).
8 Chen, et al., Isolation of High Purity Diamondoid Fractions and Components, U.S. Pat. No. 5,414,189 issued May 9, 1995.
All of the above publications and patents are herein incorporated by reference in their entirety to the same extent as if each individual publication or patent was specifically and individually indicated to be incorporated by reference in its entirety.
3. State of the Art
Tetramantanes are bridged-ring cycloalkanes having a molecular formula of C22H28. The compounds have a xe2x80x9cdiamondoidxe2x80x9d topology, which means their carbon atom arrangement is superimposable on a fragment of the diamond lattice (FIG. 1). There are four possible tetramantane isomers, each possessing a different 3-dimensional structure: iso-tetramantane, anti-tetramantane and two enantiomers of skew-tetramantane (skew-tetramantane A and skew-tetramantane B). The anti- and skew-tetramantane each possess two quaternary carbon atoms while the iso- form has three quaternary carbon atoms (FIG. 7). Alternative naming systems proposed for these tetramantanes are [1(2)3] for iso-, [121] for anti-, and [123] A and B for skew- according to Balaban et al.7 
Academic chemists have focused research on the interplay between physical and chemical properties of diamondoids. Lower diamoidids such as adamantane and diamantane, have been studied to elucidate structure-activity relationships in carbocations and radicals.3 Process engineers have directed efforts toward removing diamondoids from hydrocarbon gas streams because these compounds cause problems during the production of hydrocarbonaceous materials by solidifying in pipes and other pieces of equipment2.
The literature contains little information regarding the practical application of tetramantanes. This fact is probably due to extreme difficulties encountered in either their isolation or synthesis. Lin and Wilk, for example, discuss the presence of tetramantanes in a gas condensate.1 The researchers postulate the existence of the compounds based on a mass spectrometry fragmentation pattern. They did not, however, report the isolation of a single tetramantane. McKervey et al. discuss an extremely low yielding synthesis of anti-tetramantane.3 The procedure involves a complex starting material and employs drastic reaction conditions (e.g., gas phase on platinum at 360xc2x0 C.).
Among other properties, diamondoids have by far the most thermodynamically stable structures of all possible hydrocarbons that possess their molecular formulas due to the fact that diamondoids have the same internal xe2x80x9ccrystalline latticexe2x80x9d structure as diamonds. It is well established that diamonds exhibit extremely high tensile strength, extremely low chemical reactivity, electrical resistivity greater than aluminum trioxide (Al2O3) and excellent thermal conductivity.
In addition, based on theoretical considerations, the tetramantanes have sizes in the nanometer range and, in view of the properties noted above, the inventors contemplate that such compounds would have utility in micro- and molecular-electronics and nanotechnology applications. In particular, the rigidity, strength, stability, thermal conductivity, variety of structural forms and multiple attachment sites shown by these molecules make possible accurate construction of robust, durable, precision devices with nanometer dimensions. The various tetramantanes are three-dimensional nanometer-sized units showing different diamond lattice arrangements. This translates into a variety of rigid shapes and sizes for the four tetramantanes. For example, [1(2)3] tetramantane is pedestal-shaped, [121] tetramantane has a block-like structure. The two enantiomers of [123] have left and right handed screw-like structures. It has been estimated that MicroElectroMechanical Systems (MEMs) constructed out of diamond should last 10,000 times longer than current polysilicon MEMs, and diamond is chemically benign and would not promote allergic reactions in biomedical applications.6 Again, the inventors contemplate that tetramantane would have similar attractive properties. Furthermore, some of the isomers of tetramantane ([123] A and B) possess chirality, offering opportunities for making nanotechnology objects of great structural specificity with useful optical properties. Applications of these tetramantanes include molecular electronics, photonic devices, nanomechanical devices, nanostructured polymers and other materials.
In view of the above, there is an ongoing need in the art to provide for compositions comprising one or more tetramantanes, where anti-tetramantane is not the only tetramantane component in the compositions.
Accordingly, in one of its composition aspects, this invention is directed to a composition comprising one or more tetramantane components wherein said composition comprises at least about 50 weight percent tetramantane components based on the total weight of the diamondoids in the composition, where anti-tetramantane is not the only tetramantane component in the composition.
In another of its composition aspects, the compositions preferably comprise one or more tetramantane components wherein the tetramantane components make up from about 50 to 100 weight percent, preferably about 70 to 100 weight percent, more preferably about 90 to 100 weight percent and even more preferably about 95 to 100 weight percent of the total weight of the diamondoids in the compositions, where anti-tetramantane is not the only tetramantane component in the composition.
In another of its composition aspects, the compositions comprise at least about 10 weight percent and preferably at least about 20 weight percent of tetramantanes based on the total weight of the composition. Other compositions of this invention contain from 50 to 100 weight percent, 70 to 100 weight percent, 95 to 100 weight percent and 99 to 100 weight percent of tetramantanes based on the total weight of the composition, all again with the proviso that anti-tetramantane is not the only tetramantane component in the composition.
In another of its composition aspects, the compositions preferably comprise from about 70 to 100 weight percent, more preferably from about 90 to 100 weight percent, even more preferably from about 95 to 100 weight percent and most preferably from about 99 to 100 weight percent of a single tetramantane component, including isolated optical isomers thereof, based on the total weight of the composition, where the tetramantane is iso-tetramantane, skew-tetramantane or a single enantiomer of skew-tetramantane.
When tetramantane components are of a high purity, such tetramantane components can form crystals. Thus, this invention is directed to crystals of a skew or iso tetramantane component or of a mixture of two or more tetramantane components.
This invention is also directed to novel processes for the separation and isolation of tetramantane components into recoverable fractions from a feedstock containing one or more tetramantane components and nontetramantane materials. These processes for recovering a composition enriched in tetramantane components entail removing at least a portion of the nontetramantane materials which have a boiling point below the lowest boiling tetramantane component and utilizing a subsequent separation technique to recover tetramantane components from the resulting residue. Accordingly, this aspect is directed to processes which comprise:
a) selecting a feedstock comprising recoverable amounts of tetramantane components and nontetramantane materials;
b) removing from the feedstock a sufficient amount of nontetramantane materials that have boiling points below the boiling point of the lowest boiling point tetramantane component in the feedstock under conditions to form a treated feedstock enriched in tetramantane components which can be recovered;
c) recovering tetramantane components by separating said treated feedstock formed in b) above with one or more additional separation techniques selected from the group consisting of chromatographic techniques, thermal diffusion techniques, zone refining, progressive recrystallization and size separation techniques.
In one embodiment, after the step recited in b) the treated feedstock can be thermally treated to pyrolyze at least a sufficient amount of nondiamondoid components therefrom under conditions to provide a thermally treated feedstock retaining recoverable amounts of tetramantane. Such a pyrolization step prior to step c) is useful for thermally degrading at least a portion of any materials remaining in the treated feedstock having a thermal stability lower than the tetramantane components. This pyrolysis step can be carried out before step b) if desired.